Motor Mount Block:
  1. Screw Holes
  2. Drilling
  3. Clamping

3. Drilling Holes for a DC Motor Mounting Block

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The last step of making the motor mounting block is to cut a slit in it. The slit provides a gap so that the screws can pull together the two sides of the motor hole to clamp the motor in place.

Slicing the block with a table saw to cut a gap in one side of the motor-mount block.

Slicing the block with a table saw to cut a gap in one end of the motor-mount block.

Put the mounting block onto a table saw with the screw holes parallel to the table. Slit the block across the path of the screw holes. The space created by the slit allows the screws to compress the block together.

Mounting block that clamps a motor using half-clear and half-threaded screw holes.

Mounting block that clamps a motor using half-clear and half-threaded screw holes.

Insert screws of the appropriate length. When the screw head reaches the edge of the motor block (all the way inserted), each subsequent turn will pull together the two sides, reducing the gap and reducing the diameter of the motor hole. This clamps the motor in place.

Put another way, the clear (unthreaded) portion of the screw hole does not make contact with the screw. The screw can turn freely in the top half. Eventually, the screw head (top of the screw) makes contact with the top half of the plastic block, pushing it down. Meanwhile, the threaded portion of the screw hole does make contact with the screw threads, causing it to pull up on the bottom half of the plastic block. Thus, the two halves of the block are brought together, causing it to grip the motor.

This type of mounting block is unlikely to crush a gear box or deform a motor. It provides significantly gripping forces to attach a cylindrical motor to a robot or mechanical device. Additionally, depending on how much extra space you provide on your block, there is plenty of room for mounting other things. In fact, if the motors were at one end of a long block, the remainder of the mounting block could be used as the robot’s body.

Finished mounting block with motor and wheel installed.

Finished mounting block with motor and wheel installed.

That wasn’t so difficult, was it?